Not directly related to your connection issues, but do you have to
install tl2016?
If you have it and need to preserve a stable build environment it's
reasonable to keep using it, but installing it
on a new machine or making a docker image (for others to install?) is
rather unfortunate.
For people uploading bug fixes to ctan for assorted packages, seeing
copies of old code being installed
from the "historic" archives is rather depressing to see. It just
re-distributes old bugs and increases the
overall maintenance issues.
David